Everybody likes electrostatic machines!
No Steampunk scientific laboratory should be without one.
Jake von Slatt's amazing Steampunk Workshop has a 5 part series of posts with detailed instructions for making a classic Wimshurst Machine like this one:

Using common materials, he details all the steps to create one of these archetypal machines to amaze your visitors and shock your family members.

Invented in 1880 by James Wimshurst these machines were used:

by scientists and experimenters
investigating electrostatics but also, and more significantly, by the
medical profession. Wimshurst machines with multiple sets of disks were
employed to excite X-ray tubes used in early medical imaging. Smaller
Wimshurst machines were also employed to apply electric shocks directly
to the patient. While it is unlikely that these shock treatments
actually helped the patients of the day, once you get a chance to play
with your own Wimshurst machine you will surely understand how a patient
might believe that the machine must be doing something!

Part 1 - Overview, Materials, and Tools

When assembling a laboratory, the gentleman or lady experimenter
should be sure to include a Wimshurst electrostatic generating machine.
Not only will this device serve tirelessly for investigations in the
field of natural philosophy, interesting parlor games such as the electric kiss
are also possible! Herein we will demonstrate the construction of such a
Wimshurst machine with materials easily acquired from your local home
center and hardware store.

Introduction:

Electrostatic machines have always seemed a little like magic to me.
I've worked and played with electronics since I was about 6 years old,
so I have a thorough understanding of induction and electromagnetism.
However, electrostatics are a different thing entirely. These machines
that create high voltage charges don't have the familiar coils of copper
wire, permanent magnets, and commutators of conventional generators.
They are made from brass, glass, and wood, and look more mechanical then
electrical. But the coolest thing about electrostatic machines is that
you can feel them working. As you begin to crank a Wimshurst
machine you will hear it start to crackle and hiss with energy, you will
smell the sharp scent of ozone produced and you'll feel the hair on
your arm stand up as the Leyden jars charge.

Functional Overview:

The main components of a Wimshurst Influence machine are a pair of counter rotating disks with metal strips or sectors, a pair of charge collecting combs, and a pair of neutralizing bars with
conductive brushes that contact the sectors. We're all familiar with
the static shocks we receive after getting up from our seat and touching
a door knob when the weather is dry. That act of separating your
posterior from your chair causes a charge imbalance; a Wimshurst machine
is essentially an idealized series of posteriors and chairs endlessly
sitting and standing with a pair of collecting comb to gather the charge
produced so that something useful may be done with it.
Our machine will be built from materials readily available at your
local home center and hardware store and can be assembled using common
hand tools. The most complicated operations will include some soldering
but you will soon discover that attaching brass balls and rods in this
manner is much easier then soldering integrated circuits or working with
surface mount devices. However, it will require a somewhat larger iron
and perhaps a small torch.